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POUnable to call methods of a custom view (canvasview) from Activity or class
 

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  1. POUnable to call methods of a custom view (canvasview) from Activity or class
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    <p>I'm unable to call methods of a custom view ("canvasview") from the Activity that sets the layout including the view. I can't even call canvasview's "getters" from the activity.</p> <p>Also, I'm passing the view to a custom class (that does not extend Activity), and I can't call canvasview's methods also from my custom class.</p> <p>I'm not sure what I'm doing wrong...</p> <p><strong>GameActivity.java:</strong></p> <pre><code>public class GameActivity extends Activity implements OnClickListener { private View canvasview; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.game_layout); canvasview = (View) findViewById(R.id.canvasview); // Eclipse displays ERROR con those 2 method calls: int w = canvasview.get_canvaswidth(); int h = canvasview.get_canvasheight(); (...) </code></pre> <p><strong>game_layout.xml:</strong></p> <pre><code>&lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/LinearLayout2" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context=".GameActivity" &gt; (...) &lt;com.example.test.CanvasView android:id="@+id/canvasview" android:layout_width="wrap_content" android:layout_height="wrap_content" /&gt; &lt;/LinearLayout&gt; </code></pre> <p><strong>CanvasView.java:</strong></p> <pre><code>public class CanvasView extends View { private Context context; private View view; private int canvaswidth; private int canvasheight; public CanvasView(Context context, AttributeSet attrs) { super(context, attrs); this.context = context; this.view = this; } @Override protected void onSizeChanged(int width, int height, int old_width, int old_height) { this.canvaswidth = width; this.canvasheight = height; super.onSizeChanged(width, height, old_width, old_height); } public int get_canvaswidth() { return this.canvaswidth; } public int get_canvasheight() { return this.canvasheight; } </code></pre> <p>I'm quite confused with this :?</p> <p>I also have another class (it does not extend "Activity") that receives in the constructor a reference to canvasview and is also unable to "resolve" it :?</p> <p>Thanks, sorry if the question is too obvious, I'm starting with Java and those kind of things are quite confusing to me ...</p> <p><strong>EDIT:</strong></p> <p>While at bed (03:00AM), thinking about it, I've noticed that Eclipse marks the line as an error because the View object does not really have the method get_canvaswidth(). Only the child "CanvasView" method has it. Thus, my problem can be solved with <strong>upcast</strong>: </p> <pre><code>int w = ((CanvasView) canvasview).get_canvaswidth(); </code></pre> <p>I mean that I receive a view as parameter, but as I now it's really a view child, I should be able to use upcast to call "child's" methods. Now eclipse does not generate errors <strong>but</strong> w and h always report 0 :-? . I've also tested of not using upcast as has been suggested in an answer, and sending and receiving CanvasView objects in the calls and I also get 0 for both :?</p>
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